A micro-scale biosensor for the detection of bacillus stearothermophilus spore germination

Abstract

Germination of Bacillus Stearothermophilus bacterial spores is being used as a marker in sterilization monitoring systems to verify the success of sterilization processes in healthcare facilities. Such systems mainly employ optical detection techniques that are expensive and time consuming. This work presents the first micro-scale biosensing platform that is capable of detecting this specific spore germination through impedance measurements. Starting from theoretical calculations on ion concentrations, a simulation model is built on COMSOL software to analyze the conductance change of the medium during germination. It has been demonstrated that even 1% germination ion yield results in a 5-fold drop in germinant solution resistance, reaching up to more than two orders of magnitude decrease when the spores are fully germinated. A microfluidic biosensor consisting of interdigitated electrodes was designed, and a fabrication approach has been presented. This device, when fully fabricated, poses an inexpensive solution that can provide sterilization verification results in under 10 minutes.